The present invention relates to a concrete finishing machine having a raiseable pan drag apparatus associated with the machine which is independently operable to engage the concrete to finish and seal the concrete surface.
Concrete leveling or finishing machines are utilized for paving highways, streets or airport runways and generally include a leveling and surfacing carriage or unit which is moveable transversely back and forth across the plane of the leveling machine to engage the concrete on the street, runway or roadway to level and finish the concrete to the grade profile. Typically, such concrete leveling machines include a pan drag apparatus extending rearwardly from the moveable carriage or leveling unit. The pan drag device engages the leveled concrete to finish and seal the concrete surface. However, when paving streets, airports or highways, box-outs often exist in the prepared roadway where future manhole covers or runway marker lights will be located. The box-outs are generally one to four inches higher than the finished concrete grade. When the concrete leveling machine engages a box-out in the roadway, it is necessary to raise and lower the carriage or finishing unit to clear the box-out. Such raising and lowering of the carriage unit does not however disengage the suspended pan drag device that trails the carriage unit to contact the concrete surface. Accordingly, the pan drag device must also be raised to clear the box-out. Such raising and lowering of the pan drag apparatus must be done manually by the operator of the leveling machine. This process consumes valuable labor time and requires the shut down of the leveling machine to disengage and raise the pan drag device from the concrete surface to clear the box-outs.
Additionally, in some paving operations, the paving specification may require that a steel reinforcement grid or mat be positioned within the center of the poured concrete slab. For example, if the poured concrete slab is to be ten inches deep with a reinforcement grid positioned intermediate the thickness of the slab, the operator of the concrete leveling machine would disengage and raise the pan drag device and roughly finish the concrete slab to a depth of about five inches for a distance of seventy-five to one hundred feet. Thereafter, the leveling machine is returned to the starting point and the steel reinforcement mat or grid is positioned on the leveled five inch bed of poured concrete. Then, the second lift of concrete is poured over the reinforced grid and the leveling machine is now engaged with the concrete to level the same. This process requires additional time to manually lower the pan drag device to engage the finished concrete surface to seal the finished surface. This results in extended down time of the leveling machine which is time consuming and increases the costs of pouring, leveling and finishing concrete.